The present invention relates to a closed compressor in which a connecting rod is connected to a piston with a ball of the connecting rod seated in a ball seat formed in the piston.
As a conventional technology, there has been a closed compressor as disclosed in JP-B No. H2-36794.
In FIG. 19 showing the conventional technology of the closed compressor used in a refrigeration cycle, an electric motor 22 and a compressor mechanism section 23 are housed in a closed housing 21.
The compressor mechanism section 23 has an eccentrically rotating crankshaft 26 on the top end of a shaft 25 axially supported on a frame 24. A piston 28 reciprocally sliding in the cylinder 27 is connected to the crankshaft 26 through a connecting rod 29.
The connecting rod 29 and the piston 28, as shown in FIG. 20, are connected through a ball joint 30.
The connecting rod 29 includes a rod portion 33 on both ends of which a ball portion 31 and a ring portion 32 which is connected with the crankshaft 26 are fixedly attached.
The piston 28 is provided with a ball seat 34 in which the ball portion 31 of the connecting rod 29 seats. Before the ball portion 31 seats in the ball seat 34, a cover section provided at the ball seat 34 for covering the ball portion 31 is in the open position to allow insertion of the ball portion 31. After the insertion of the ball portion 31 into the ball seat 34 with the cover section in the open position, the spreading cover section of the ball seat 34 is closed and caulked (to cover the ball portion 31), so that the rod portion 33 fixedly jointed to the ball portion 31 may be rockably connected to the ball seat 34.
The ball portion 31 slides in the ball seat 34 during the operation of the closed compressor. Therefore, it is necessary to supply a lubricating oil between the ball portion 31 and the ball seat 34.
As a structure for supplying the lubricating oil between the ball portion 31 and the ball seat 34 stated above in JP-B No. H2-36794, a lubricating oil supply passage is formed by creasing the cover section of the ball seat 34 which covers the ball portion 31.
However, the structure for supplying the lubricating oil between the ball portion 31 and the ball seat 34 stated in JP-B No. H2-36794 has such a disadvantage as the lack of general versatility because a special caulking tool is needed.
There, however, are cases where, if the special tool is used, the lubricating oil supply passage of desired shape is unobtainable depending upon the opened state of the cover section of the ball seat 34.
In view of the above-described disadvantage, it is an object of this invention to provide a structure which will facilitate the assembly of the piston (ball seat) and the connecting rod (ball) and the smooth supply of lubricating oil to the ball and the ball seat.
To achieve the object, this invention has the structure that the ball portion of the connecting rod is provided with a flat section parallel with the end surface of the ring, and the piston is provided with a groove section which enables the insertion of the ball into the ball seat.
The groove section is desired to have at least the same width as the ball portion of the connecting rod which has a flat section.
Furthermore, the groove section should be formed long enough to reach at least the maximum-diameter portion of the ball seat. Since a ring portion is joined to the crankshaft which eccentrically rotates in relation to the shaft, the connecting rod assembled to the piston moves principally in a direction perpendicular to the shaft in accordance with the eccentric rotation of the crankshaft. It is, therefore, desirable to assemble the groove section of the piston in a position parallel to the shaft.
Because of the above-described structure, there is formed a space between the groove section of the piston and the flat cut portion of the connecting rod. This space serves as a lubricating oil inlet to the ball joint section. During the operation of the closed compressor, the ball section must be kept within the ball seat against the relative rotation of the piston and the connecting rod. To keep the ball section within the ball seat, it is desirable to provide a rotation restricting member for regulating the free rotation of the piston in relation to the connecting rod. The rotation restricting member must not interfere with smooth supply of the lubricating oil to the ball seat. If the lubricating oil is applied by splash-lubrication from the end of the crankshaft, it is desirable to adopt the structure that the space formed between the groove section of the piston on the crankshaft end side and the flat cut portion of the connecting rod is opened.